9/11: The Al Qaeda attacks on New York’s Twin Towers and the Pentagon in Washington on 11th September 2001, which triggered President George W Bush’s ‘War on Terror’ and the wars in Afghanistan and Iraq.

7/7: The co-ordinated bomb attacks on London by four young British men in the name of Al Qaeda, on 7th July 2005, which killed 52 people.

Al Qaeda: Terrorist group founded in 1988 by Osama Bin Laden, which committed the 9/11 attacks.

Islamic State (Daesh/IS/ISIS/ISIL): Terrorist group formed after the fall of Saddam Hussain in Iraq and the civil war in Syria. It is the most prominent recruiter of Westerners to its mission to establish its own state.